/* trees.c -- output deflated data using Huffman coding
 * Copyright (C) 1995-2012 Jean-loup Gailly
 * detect_data_type() function provided freely by Cosmin Truta, 2006
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/*
 *  ALGORITHM
 *
 *      The "deflation" process uses several Huffman trees. The more
 *      common source values are represented by shorter bit sequences.
 *
 *      Each code tree is stored in a compressed form which is itself
 * a Huffman encoding of the lengths of all the code strings (in
 * ascending order by source values).  The actual code strings are
 * reconstructed from the lengths in the inflate process, as described
 * in the deflate specification.
 *
 *  REFERENCES
 *
 *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
 *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
 *
 *      Storer, James A.
 *          Data Compression:  Methods and Theory, pp. 49-50.
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
 *
 *      Sedgewick, R.
 *          Algorithms, p290.
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
 */

/* @(#) $Id$ */

/* #define GEN_TREES_H */

#include "deflate.h"

// RB: avoid problems with SourceAnnotations.h
#define VERIFY_FORMAT_STRING
#if !defined( TYPEINFOPROJECT ) && !defined( DMAP )
	#include "idlib/sys/sys_defines.h"
#endif

#ifdef DEBUG
	#include <ctype.h>
#endif

/* ===========================================================================
 * Constants
 */

#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */

#define END_BLOCK 256
/* end of block literal code */

#define REP_3_6      16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */

#define REPZ_3_10    17
/* repeat a zero length 3-10 times  (3 bits of repeat count) */

#define REPZ_11_138  18
/* repeat a zero length 11-138 times  (7 bits of repeat count) */

local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
	= {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};

local const int extra_dbits[D_CODES] /* extra bits for each distance code */
	= {0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13};

local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
	= {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7};

local const uch bl_order[BL_CODES]
	= {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
/* The lengths of the bit length codes are sent in order of decreasing
 * probability, to avoid transmitting the lengths for unused bit length codes.
 */

/* ===========================================================================
 * Local data. These are initialized only once.
 */

#define DIST_CODE_LEN  512 /* see definition of array dist_code below */

#if defined(GEN_TREES_H) || !defined(STDC)
	/* non ANSI compilers may not accept trees.h */

	local ct_data static_ltree[L_CODES + 2];
	/* The static literal tree. Since the bit lengths are imposed, there is no
	* need for the L_CODES extra codes used during heap construction. However
	* The codes 286 and 287 are needed to build a canonical tree (see _tr_init
	* below).
	*/

	local ct_data static_dtree[D_CODES];
	/* The static distance tree. (Actually a trivial tree since all codes use
	* 5 bits.)
	*/

	uch _dist_code[DIST_CODE_LEN];
	/* Distance codes. The first 256 values correspond to the distances
	* 3 .. 258, the last 256 values correspond to the top 8 bits of
	* the 15 bit distances.
	*/

	uch _length_code[MAX_MATCH - MIN_MATCH + 1];
	/* length code for each normalized match length (0 == MIN_MATCH) */

	local int base_length[LENGTH_CODES];
	/* First normalized length for each code (0 = MIN_MATCH) */

	local int base_dist[D_CODES];
	/* First normalized distance for each code (0 = distance of 1) */

#else
	#include "trees.h"
#endif /* GEN_TREES_H */

struct static_tree_desc_s
{
	const ct_data* static_tree;  /* static tree or NULL */
	const intf* extra_bits;      /* extra bits for each code or NULL */
	int     extra_base;          /* base index for extra_bits */
	int     elems;               /* max number of elements in the tree */
	int     max_length;          /* max bit length for the codes */
};

local static_tree_desc  static_l_desc =
{static_ltree, extra_lbits, LITERALS + 1, L_CODES, MAX_BITS};

local static_tree_desc  static_d_desc =
{static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};

local static_tree_desc  static_bl_desc =
{( const ct_data* )0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};

/* ===========================================================================
 * Local (static) routines in this file.
 */

local void tr_static_init OF( ( void ) );
local void init_block     OF( ( deflate_state* s ) );
local void pqdownheap     OF( ( deflate_state* s, ct_data* tree, int k ) );
local void gen_bitlen     OF( ( deflate_state* s, tree_desc* desc ) );
local void gen_codes      OF( ( ct_data* tree, int max_code, ushf* bl_count ) );
local void build_tree     OF( ( deflate_state* s, tree_desc* desc ) );
local void scan_tree      OF( ( deflate_state* s, ct_data* tree, int max_code ) );
local void send_tree      OF( ( deflate_state* s, ct_data* tree, int max_code ) );
local int  build_bl_tree  OF( ( deflate_state* s ) );
local void send_all_trees OF( ( deflate_state* s, int lcodes, int dcodes,
								int blcodes ) );
local void compress_block OF( ( deflate_state* s, ct_data* ltree,
								ct_data* dtree ) );
local int  detect_data_type OF( ( deflate_state* s ) );
local unsigned bi_reverse OF( ( unsigned value, int length ) );
local void bi_windup      OF( ( deflate_state* s ) );
local void bi_flush       OF( ( deflate_state* s ) );
local void copy_block     OF( ( deflate_state* s, charf* buf, unsigned len,
								int header ) );

#ifdef GEN_TREES_H
	local void gen_trees_header OF( ( void ) );
#endif

#ifndef DEBUG
#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
/* Send a code of the given tree. c and tree must not have side effects */

#else /* DEBUG */
#  define send_code(s, c, tree) \
     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
       send_bits(s, tree[c].Code, tree[c].Len); }
#endif

/* ===========================================================================
 * Output a short LSB first on the stream.
 * IN assertion: there is enough room in pendingBuf.
 */
#define put_short(s, w) { \
    put_byte(s, (uch)((w) & 0xff)); \
    put_byte(s, (uch)((ush)(w) >> 8)); \
}

/* ===========================================================================
 * Send a value on a given number of bits.
 * IN assertion: length <= 16 and value fits in length bits.
 */
#ifdef DEBUG
local void send_bits      OF( ( deflate_state* s, int value, int length ) );

local void send_bits( s, value, length )
deflate_state* s;
int value;  /* value to send */
int length; /* number of bits */
{
	Tracevv( ( stderr, " l %2d v %4x ", length, value ) );
	Assert( length > 0 && length <= 15, "invalid length" );
	s->bits_sent += ( ulg )length;

	/* If not enough room in bi_buf, use (valid) bits from bi_buf and
	 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
	 * unused bits in value.
	 */
	if( s->bi_valid > ( int )Buf_size - length )
	{
		s->bi_buf |= ( ush )value << s->bi_valid;
		put_short( s, s->bi_buf );
		s->bi_buf = ( ush )value >> ( Buf_size - s->bi_valid );
		s->bi_valid += length - Buf_size;
	}
	else
	{
		s->bi_buf |= ( ush )value << s->bi_valid;
		s->bi_valid += length;
	}
}
#else /* !DEBUG */

#define send_bits(s, value, length) \
{ int len = length;\
  if (s->bi_valid > (int)Buf_size - len) {\
    int val = value;\
    s->bi_buf |= (ush)val << s->bi_valid;\
    put_short(s, s->bi_buf);\
    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
    s->bi_valid += len - Buf_size;\
  } else {\
    s->bi_buf |= (ush)(value) << s->bi_valid;\
    s->bi_valid += len;\
  }\
}
#endif /* DEBUG */


/* the arguments must not have side effects */

/* ===========================================================================
 * Initialize the various 'constant' tables.
 */
local void tr_static_init()
{
#if defined(GEN_TREES_H) || !defined(STDC)
	static int static_init_done = 0;
	int n;        /* iterates over tree elements */
	int bits;     /* bit counter */
	int length;   /* length value */
	int code;     /* code value */
	int dist;     /* distance index */
	ush bl_count[MAX_BITS + 1];
	/* number of codes at each bit length for an optimal tree */

	if( static_init_done )
	{
		return;
	}

	/* For some embedded targets, global variables are not initialized: */
#ifdef NO_INIT_GLOBAL_POINTERS
	static_l_desc.static_tree = static_ltree;
	static_l_desc.extra_bits = extra_lbits;
	static_d_desc.static_tree = static_dtree;
	static_d_desc.extra_bits = extra_dbits;
	static_bl_desc.extra_bits = extra_blbits;
#endif

	/* Initialize the mapping length (0..255) -> length code (0..28) */
	length = 0;
	for( code = 0; code < LENGTH_CODES - 1; code++ )
	{
		base_length[code] = length;
		for( n = 0; n < ( 1 << extra_lbits[code] ); n++ )
		{
			_length_code[length++] = ( uch )code;
		}
	}
	Assert( length == 256, "tr_static_init: length != 256" );
	/* Note that the length 255 (match length 258) can be represented
	 * in two different ways: code 284 + 5 bits or code 285, so we
	 * overwrite length_code[255] to use the best encoding:
	 */
	_length_code[length - 1] = ( uch )code;

	/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
	dist = 0;
	for( code = 0 ; code < 16; code++ )
	{
		base_dist[code] = dist;
		for( n = 0; n < ( 1 << extra_dbits[code] ); n++ )
		{
			_dist_code[dist++] = ( uch )code;
		}
	}
	Assert( dist == 256, "tr_static_init: dist != 256" );
	dist >>= 7; /* from now on, all distances are divided by 128 */
	for( ; code < D_CODES; code++ )
	{
		base_dist[code] = dist << 7;
		for( n = 0; n < ( 1 << ( extra_dbits[code] - 7 ) ); n++ )
		{
			_dist_code[256 + dist++] = ( uch )code;
		}
	}
	Assert( dist == 256, "tr_static_init: 256+dist != 512" );

	/* Construct the codes of the static literal tree */
	for( bits = 0; bits <= MAX_BITS; bits++ )
	{
		bl_count[bits] = 0;
	}
	n = 0;
	while( n <= 143 )
	{
		static_ltree[n++].Len = 8, bl_count[8]++;
	}
	while( n <= 255 )
	{
		static_ltree[n++].Len = 9, bl_count[9]++;
	}
	while( n <= 279 )
	{
		static_ltree[n++].Len = 7, bl_count[7]++;
	}
	while( n <= 287 )
	{
		static_ltree[n++].Len = 8, bl_count[8]++;
	}
	/* Codes 286 and 287 do not exist, but we must include them in the
	 * tree construction to get a canonical Huffman tree (longest code
	 * all ones)
	 */
	gen_codes( ( ct_data* )static_ltree, L_CODES + 1, bl_count );

	/* The static distance tree is trivial: */
	for( n = 0; n < D_CODES; n++ )
	{
		static_dtree[n].Len = 5;
		static_dtree[n].Code = bi_reverse( ( unsigned )n, 5 );
	}
	static_init_done = 1;

#  ifdef GEN_TREES_H
	gen_trees_header();
#  endif
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
}

/* ===========================================================================
 * Genererate the file trees.h describing the static trees.
 */
#ifdef GEN_TREES_H
#ifndef DEBUG
	#include <stdio.h>
#endif

#  define SEPARATOR(i, last, width) \
      ((i) == (last)? "\n};\n\n" :    \
       ((i) % (width) == (width)-1 ? ",\n" : ", "))

void gen_trees_header()
{
	FILE* header = fopen( "trees.h", "w" );
	int i;

	Assert( header != NULL, "Can't open trees.h" );
	fprintf( header,
			 "/* header created automatically with -DGEN_TREES_H */\n\n" );

	fprintf( header, "local const ct_data static_ltree[L_CODES+2] = {\n" );
	for( i = 0; i < L_CODES + 2; i++ )
	{
		fprintf( header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
				 static_ltree[i].Len, SEPARATOR( i, L_CODES + 1, 5 ) );
	}

	fprintf( header, "local const ct_data static_dtree[D_CODES] = {\n" );
	for( i = 0; i < D_CODES; i++ )
	{
		fprintf( header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
				 static_dtree[i].Len, SEPARATOR( i, D_CODES - 1, 5 ) );
	}

	fprintf( header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n" );
	for( i = 0; i < DIST_CODE_LEN; i++ )
	{
		fprintf( header, "%2u%s", _dist_code[i],
				 SEPARATOR( i, DIST_CODE_LEN - 1, 20 ) );
	}

	fprintf( header,
			 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n" );
	for( i = 0; i < MAX_MATCH - MIN_MATCH + 1; i++ )
	{
		fprintf( header, "%2u%s", _length_code[i],
				 SEPARATOR( i, MAX_MATCH - MIN_MATCH, 20 ) );
	}

	fprintf( header, "local const int base_length[LENGTH_CODES] = {\n" );
	for( i = 0; i < LENGTH_CODES; i++ )
	{
		fprintf( header, "%1u%s", base_length[i],
				 SEPARATOR( i, LENGTH_CODES - 1, 20 ) );
	}

	fprintf( header, "local const int base_dist[D_CODES] = {\n" );
	for( i = 0; i < D_CODES; i++ )
	{
		fprintf( header, "%5u%s", base_dist[i],
				 SEPARATOR( i, D_CODES - 1, 10 ) );
	}

	fclose( header );
}
#endif /* GEN_TREES_H */

/* ===========================================================================
 * Initialize the tree data structures for a new zlib stream.
 */
void ZLIB_INTERNAL _tr_init( s )
deflate_state* s;
{
	tr_static_init();

	s->l_desc.dyn_tree = s->dyn_ltree;
	s->l_desc.stat_desc = &static_l_desc;

	s->d_desc.dyn_tree = s->dyn_dtree;
	s->d_desc.stat_desc = &static_d_desc;

	s->bl_desc.dyn_tree = s->bl_tree;
	s->bl_desc.stat_desc = &static_bl_desc;

	s->bi_buf = 0;
	s->bi_valid = 0;
#ifdef DEBUG
	s->compressed_len = 0L;
	s->bits_sent = 0L;
#endif

	/* Initialize the first block of the first file: */
	init_block( s );
}

/* ===========================================================================
 * Initialize a new block.
 */
local void init_block( s )
deflate_state* s;
{
	int n; /* iterates over tree elements */

	/* Initialize the trees. */
	for( n = 0; n < L_CODES;  n++ )
	{
		s->dyn_ltree[n].Freq = 0;
	}
	for( n = 0; n < D_CODES;  n++ )
	{
		s->dyn_dtree[n].Freq = 0;
	}
	for( n = 0; n < BL_CODES; n++ )
	{
		s->bl_tree[n].Freq = 0;
	}

	s->dyn_ltree[END_BLOCK].Freq = 1;
	s->opt_len = s->static_len = 0L;
	s->last_lit = s->matches = 0;
}

#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */


/* ===========================================================================
 * Remove the smallest element from the heap and recreate the heap with
 * one less element. Updates heap and heap_len.
 */
#define pqremove(s, tree, top) \
{\
    top = s->heap[SMALLEST]; \
    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
    pqdownheap(s, tree, SMALLEST); \
}

/* ===========================================================================
 * Compares to subtrees, using the tree depth as tie breaker when
 * the subtrees have equal frequency. This minimizes the worst case length.
 */
#define smaller(tree, n, m, depth) \
   (tree[n].Freq < tree[m].Freq || \
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))

/* ===========================================================================
 * Restore the heap property by moving down the tree starting at node k,
 * exchanging a node with the smallest of its two sons if necessary, stopping
 * when the heap property is re-established (each father smaller than its
 * two sons).
 */
local void pqdownheap( s, tree, k )
deflate_state* s;
ct_data* tree;  /* the tree to restore */
int k;               /* node to move down */
{
	int v = s->heap[k];
	int j = k << 1;  /* left son of k */
	while( j <= s->heap_len )
	{
		/* Set j to the smallest of the two sons: */
		if( j < s->heap_len &&
				smaller( tree, s->heap[j + 1], s->heap[j], s->depth ) )
		{
			j++;
		}
		/* Exit if v is smaller than both sons */
		if( smaller( tree, v, s->heap[j], s->depth ) )
		{
			break;
		}

		/* Exchange v with the smallest son */
		s->heap[k] = s->heap[j];
		k = j;

		/* And continue down the tree, setting j to the left son of k */
		j <<= 1;
	}
	s->heap[k] = v;
}

/* ===========================================================================
 * Compute the optimal bit lengths for a tree and update the total bit length
 * for the current block.
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
 *    above are the tree nodes sorted by increasing frequency.
 * OUT assertions: the field len is set to the optimal bit length, the
 *     array bl_count contains the frequencies for each bit length.
 *     The length opt_len is updated; static_len is also updated if stree is
 *     not null.
 */
local void gen_bitlen( s, desc )
deflate_state* s;
tree_desc* desc;    /* the tree descriptor */
{
	ct_data* tree        = desc->dyn_tree;
	int max_code         = desc->max_code;
	const ct_data* stree = desc->stat_desc->static_tree;
	const intf* extra    = desc->stat_desc->extra_bits;
	int base             = desc->stat_desc->extra_base;
	int max_length       = desc->stat_desc->max_length;
	int h;              /* heap index */
	int n, m;           /* iterate over the tree elements */
	int bits;           /* bit length */
	int xbits;          /* extra bits */
	ush f;              /* frequency */
	int overflow = 0;   /* number of elements with bit length too large */

	for( bits = 0; bits <= MAX_BITS; bits++ )
	{
		s->bl_count[bits] = 0;
	}

	/* In a first pass, compute the optimal bit lengths (which may
	 * overflow in the case of the bit length tree).
	 */
	tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */

	for( h = s->heap_max + 1; h < HEAP_SIZE; h++ )
	{
		n = s->heap[h];
		bits = tree[tree[n].Dad].Len + 1;
		if( bits > max_length )
		{
			bits = max_length, overflow++;
		}
		tree[n].Len = ( ush )bits;
		/* We overwrite tree[n].Dad which is no longer needed */

		if( n > max_code )
		{
			continue;    /* not a leaf node */
		}

		s->bl_count[bits]++;
		xbits = 0;
		if( n >= base )
		{
			xbits = extra[n - base];
		}
		f = tree[n].Freq;
		s->opt_len += ( ulg )f * ( bits + xbits );
		if( stree )
		{
			s->static_len += ( ulg )f * ( stree[n].Len + xbits );
		}
	}
	if( overflow == 0 )
	{
		return;
	}

	Trace( ( stderr, "\nbit length overflow\n" ) );
	/* This happens for example on obj2 and pic of the Calgary corpus */

	/* Find the first bit length which could increase: */
	do
	{
		bits = max_length - 1;
		while( s->bl_count[bits] == 0 )
		{
			bits--;
		}
		s->bl_count[bits]--;      /* move one leaf down the tree */
		s->bl_count[bits + 1] += 2; /* move one overflow item as its brother */
		s->bl_count[max_length]--;
		/* The brother of the overflow item also moves one step up,
		 * but this does not affect bl_count[max_length]
		 */
		overflow -= 2;
	}
	while( overflow > 0 );

	/* Now recompute all bit lengths, scanning in increasing frequency.
	 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
	 * lengths instead of fixing only the wrong ones. This idea is taken
	 * from 'ar' written by Haruhiko Okumura.)
	 */
	for( bits = max_length; bits != 0; bits-- )
	{
		n = s->bl_count[bits];
		while( n != 0 )
		{
			m = s->heap[--h];
			if( m > max_code )
			{
				continue;
			}
			if( ( unsigned ) tree[m].Len != ( unsigned ) bits )
			{
				Trace( ( stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits ) );
				s->opt_len += ( ( long )bits - ( long )tree[m].Len )
							  * ( long )tree[m].Freq;
				tree[m].Len = ( ush )bits;
			}
			n--;
		}
	}
}

/* ===========================================================================
 * Generate the codes for a given tree and bit counts (which need not be
 * optimal).
 * IN assertion: the array bl_count contains the bit length statistics for
 * the given tree and the field len is set for all tree elements.
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
local void gen_codes( tree, max_code, bl_count )
ct_data* tree;             /* the tree to decorate */
int max_code;              /* largest code with non zero frequency */
ushf* bl_count;            /* number of codes at each bit length */
{
	ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
	ush code = 0;              /* running code value */
	int bits;                  /* bit index */
	int n;                     /* code index */

	/* The distribution counts are first used to generate the code values
	 * without bit reversal.
	 */
	for( bits = 1; bits <= MAX_BITS; bits++ )
	{
		next_code[bits] = code = ( code + bl_count[bits - 1] ) << 1;
	}
	/* Check that the bit counts in bl_count are consistent. The last code
	 * must be all ones.
	 */
	Assert( code + bl_count[MAX_BITS] - 1 == ( 1 << MAX_BITS ) - 1,
			"inconsistent bit counts" );
	Tracev( ( stderr, "\ngen_codes: max_code %d ", max_code ) );

	for( n = 0;  n <= max_code; n++ )
	{
		int len = tree[n].Len;
		if( len == 0 )
		{
			continue;
		}
		/* Now reverse the bits */
		tree[n].Code = bi_reverse( next_code[len]++, len );

		Tracecv( tree != static_ltree, ( stderr, "\nn %3d %c l %2d c %4x (%x) ",
										 n, ( isgraph( n ) ? n : ' ' ), len, tree[n].Code, next_code[len] - 1 ) );
	}
}

/* ===========================================================================
 * Construct one Huffman tree and assigns the code bit strings and lengths.
 * Update the total bit length for the current block.
 * IN assertion: the field freq is set for all tree elements.
 * OUT assertions: the fields len and code are set to the optimal bit length
 *     and corresponding code. The length opt_len is updated; static_len is
 *     also updated if stree is not null. The field max_code is set.
 */
local void build_tree( s, desc )
deflate_state* s;
tree_desc* desc; /* the tree descriptor */
{
	ct_data* tree         = desc->dyn_tree;
	const ct_data* stree  = desc->stat_desc->static_tree;
	int elems             = desc->stat_desc->elems;
	int n, m;          /* iterate over heap elements */
	int max_code = -1; /* largest code with non zero frequency */
	int node;          /* new node being created */

	/* Construct the initial heap, with least frequent element in
	 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
	 * heap[0] is not used.
	 */
	s->heap_len = 0, s->heap_max = HEAP_SIZE;

	for( n = 0; n < elems; n++ )
	{
		if( tree[n].Freq != 0 )
		{
			s->heap[++( s->heap_len )] = max_code = n;
			s->depth[n] = 0;
		}
		else
		{
			tree[n].Len = 0;
		}
	}

	/* The pkzip format requires that at least one distance code exists,
	 * and that at least one bit should be sent even if there is only one
	 * possible code. So to avoid special checks later on we force at least
	 * two codes of non zero frequency.
	 */
	while( s->heap_len < 2 )
	{
		node = s->heap[++( s->heap_len )] = ( max_code < 2 ? ++max_code : 0 );
		tree[node].Freq = 1;
		s->depth[node] = 0;
		s->opt_len--;
		if( stree )
		{
			s->static_len -= stree[node].Len;
		}
		/* node is 0 or 1 so it does not have extra bits */
	}
	desc->max_code = max_code;

	/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
	 * establish sub-heaps of increasing lengths:
	 */
	for( n = s->heap_len / 2; n >= 1; n-- )
	{
		pqdownheap( s, tree, n );
	}

	/* Construct the Huffman tree by repeatedly combining the least two
	 * frequent nodes.
	 */
	node = elems;              /* next internal node of the tree */
	do
	{
		pqremove( s, tree, n ); /* n = node of least frequency */
		m = s->heap[SMALLEST]; /* m = node of next least frequency */

		s->heap[--( s->heap_max )] = n; /* keep the nodes sorted by frequency */
		s->heap[--( s->heap_max )] = m;

		/* Create a new node father of n and m */
		tree[node].Freq = tree[n].Freq + tree[m].Freq;
		s->depth[node] = ( uch )( ( s->depth[n] >= s->depth[m] ?
									s->depth[n] : s->depth[m] ) + 1 );
		tree[n].Dad = tree[m].Dad = ( ush )node;
#ifdef DUMP_BL_TREE
		if( tree == s->bl_tree )
		{
			fprintf( stderr, "\nnode %d(%d), sons %d(%d) %d(%d)",
					 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq );
		}
#endif
		/* and insert the new node in the heap */
		s->heap[SMALLEST] = node++;
		pqdownheap( s, tree, SMALLEST );

	}
	while( s->heap_len >= 2 );

	s->heap[--( s->heap_max )] = s->heap[SMALLEST];

	/* At this point, the fields freq and dad are set. We can now
	 * generate the bit lengths.
	 */
	gen_bitlen( s, ( tree_desc* )desc );

	/* The field len is now set, we can generate the bit codes */
	gen_codes( ( ct_data* )tree, max_code, s->bl_count );
}

/* ===========================================================================
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree.
 */
local void scan_tree( s, tree, max_code )
deflate_state* s;
ct_data* tree;   /* the tree to be scanned */
int max_code;    /* and its largest code of non zero frequency */
{
	int n;                     /* iterates over all tree elements */
	int prevlen = -1;          /* last emitted length */
	int curlen;                /* length of current code */
	int nextlen = tree[0].Len; /* length of next code */
	int count = 0;             /* repeat count of the current code */
	int max_count = 7;         /* max repeat count */
	int min_count = 4;         /* min repeat count */

	if( nextlen == 0 )
	{
		max_count = 138, min_count = 3;
	}
	tree[max_code + 1].Len = ( ush )0xffff; /* guard */

	for( n = 0; n <= max_code; n++ )
	{
		curlen = nextlen;
		nextlen = tree[n + 1].Len;
		if( ++count < max_count && curlen == nextlen )
		{
			continue;
		}
		else if( count < min_count )
		{
			s->bl_tree[curlen].Freq += count;
		}
		else if( curlen != 0 )
		{
			if( curlen != prevlen )
			{
				s->bl_tree[curlen].Freq++;
			}
			s->bl_tree[REP_3_6].Freq++;
		}
		else if( count <= 10 )
		{
			s->bl_tree[REPZ_3_10].Freq++;
		}
		else
		{
			s->bl_tree[REPZ_11_138].Freq++;
		}
		count = 0;
		prevlen = curlen;
		if( nextlen == 0 )
		{
			max_count = 138, min_count = 3;
		}
		else if( curlen == nextlen )
		{
			max_count = 6, min_count = 3;
		}
		else
		{
			max_count = 7, min_count = 4;
		}
	}
}

/* ===========================================================================
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
local void send_tree( s, tree, max_code )
deflate_state* s;
ct_data* tree; /* the tree to be scanned */
int max_code;       /* and its largest code of non zero frequency */
{
	int n;                     /* iterates over all tree elements */
	int prevlen = -1;          /* last emitted length */
	int curlen;                /* length of current code */
	int nextlen = tree[0].Len; /* length of next code */
	int count = 0;             /* repeat count of the current code */
	int max_count = 7;         /* max repeat count */
	int min_count = 4;         /* min repeat count */

	/* tree[max_code+1].Len = -1; */  /* guard already set */
	if( nextlen == 0 )
	{
		max_count = 138, min_count = 3;
	}

	for( n = 0; n <= max_code; n++ )
	{
		curlen = nextlen;
		nextlen = tree[n + 1].Len;
		if( ++count < max_count && curlen == nextlen )
		{
			continue;
		}
		else if( count < min_count )
		{
			do
			{
				send_code( s, curlen, s->bl_tree );
			}
			while( --count != 0 );

		}
		else if( curlen != 0 )
		{
			if( curlen != prevlen )
			{
				send_code( s, curlen, s->bl_tree );
				count--;
			}
			Assert( count >= 3 && count <= 6, " 3_6?" );
			send_code( s, REP_3_6, s->bl_tree );
			send_bits( s, count - 3, 2 );

		}
		else if( count <= 10 )
		{
			send_code( s, REPZ_3_10, s->bl_tree );
			send_bits( s, count - 3, 3 );

		}
		else
		{
			send_code( s, REPZ_11_138, s->bl_tree );
			send_bits( s, count - 11, 7 );
		}
		count = 0;
		prevlen = curlen;
		if( nextlen == 0 )
		{
			max_count = 138, min_count = 3;
		}
		else if( curlen == nextlen )
		{
			max_count = 6, min_count = 3;
		}
		else
		{
			max_count = 7, min_count = 4;
		}
	}
}

/* ===========================================================================
 * Construct the Huffman tree for the bit lengths and return the index in
 * bl_order of the last bit length code to send.
 */
local int build_bl_tree( s )
deflate_state* s;
{
	int max_blindex;  /* index of last bit length code of non zero freq */

	/* Determine the bit length frequencies for literal and distance trees */
	scan_tree( s, ( ct_data* )s->dyn_ltree, s->l_desc.max_code );
	scan_tree( s, ( ct_data* )s->dyn_dtree, s->d_desc.max_code );

	/* Build the bit length tree: */
	build_tree( s, ( tree_desc* )( &( s->bl_desc ) ) );
	/* opt_len now includes the length of the tree representations, except
	 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
	 */

	/* Determine the number of bit length codes to send. The pkzip format
	 * requires that at least 4 bit length codes be sent. (appnote.txt says
	 * 3 but the actual value used is 4.)
	 */
	for( max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex-- )
	{
		if( s->bl_tree[bl_order[max_blindex]].Len != 0 )
		{
			break;
		}
	}
	/* Update opt_len to include the bit length tree and counts */
	s->opt_len += 3 * ( max_blindex + 1 ) + 5 + 5 + 4;
	Tracev( ( stderr, "\ndyn trees: dyn %ld, stat %ld",
			  s->opt_len, s->static_len ) );

	return max_blindex;
}

/* ===========================================================================
 * Send the header for a block using dynamic Huffman trees: the counts, the
 * lengths of the bit length codes, the literal tree and the distance tree.
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
 */
local void send_all_trees( s, lcodes, dcodes, blcodes )
deflate_state* s;
int lcodes, dcodes, blcodes; /* number of codes for each tree */
{
	int rank;                    /* index in bl_order */

	Assert( lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes" );
	Assert( lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
			"too many codes" );
	Tracev( ( stderr, "\nbl counts: " ) );
	send_bits( s, lcodes - 257, 5 ); /* not +255 as stated in appnote.txt */
	send_bits( s, dcodes - 1,   5 );
	send_bits( s, blcodes - 4,  4 ); /* not -3 as stated in appnote.txt */
	for( rank = 0; rank < blcodes; rank++ )
	{
		Tracev( ( stderr, "\nbl code %2d ", bl_order[rank] ) );
		send_bits( s, s->bl_tree[bl_order[rank]].Len, 3 );
	}
	Tracev( ( stderr, "\nbl tree: sent %ld", s->bits_sent ) );

	send_tree( s, ( ct_data* )s->dyn_ltree, lcodes - 1 ); /* literal tree */
	Tracev( ( stderr, "\nlit tree: sent %ld", s->bits_sent ) );

	send_tree( s, ( ct_data* )s->dyn_dtree, dcodes - 1 ); /* distance tree */
	Tracev( ( stderr, "\ndist tree: sent %ld", s->bits_sent ) );
}

/* ===========================================================================
 * Send a stored block
 */
void ZLIB_INTERNAL _tr_stored_block( s, buf, stored_len, last )
deflate_state* s;
charf* buf;       /* input block */
ulg stored_len;   /* length of input block */
int last;         /* one if this is the last block for a file */
{
	send_bits( s, ( STORED_BLOCK << 1 ) + last, 3 ); /* send block type */
#ifdef DEBUG
	s->compressed_len = ( s->compressed_len + 3 + 7 ) & ( ulg )~7L;
	s->compressed_len += ( stored_len + 4 ) << 3;
#endif
	copy_block( s, buf, ( unsigned )stored_len, 1 ); /* with header */
}

/* ===========================================================================
 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
 */
void ZLIB_INTERNAL _tr_flush_bits( s )
deflate_state* s;
{
	bi_flush( s );
}

/* ===========================================================================
 * Send one empty static block to give enough lookahead for inflate.
 * This takes 10 bits, of which 7 may remain in the bit buffer.
 */
void ZLIB_INTERNAL _tr_align( s )
deflate_state* s;
{
	send_bits( s, STATIC_TREES << 1, 3 );
	send_code( s, END_BLOCK, static_ltree );
#ifdef DEBUG
	s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
#endif
	bi_flush( s );
}

/* ===========================================================================
 * Determine the best encoding for the current block: dynamic trees, static
 * trees or store, and output the encoded block to the zip file.
 */
void ZLIB_INTERNAL _tr_flush_block( s, buf, stored_len, last )
deflate_state* s;
charf* buf;       /* input block, or NULL if too old */
ulg stored_len;   /* length of input block */
int last;         /* one if this is the last block for a file */
{
	ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
	int max_blindex = 0;  /* index of last bit length code of non zero freq */

	/* Build the Huffman trees unless a stored block is forced */
	if( s->level > 0 )
	{

		/* Check if the file is binary or text */
		if( s->strm->data_type == Z_UNKNOWN )
		{
			s->strm->data_type = detect_data_type( s );
		}

		/* Construct the literal and distance trees */
		build_tree( s, ( tree_desc* )( &( s->l_desc ) ) );
		Tracev( ( stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
				  s->static_len ) );

		build_tree( s, ( tree_desc* )( &( s->d_desc ) ) );
		Tracev( ( stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
				  s->static_len ) );
		/* At this point, opt_len and static_len are the total bit lengths of
		 * the compressed block data, excluding the tree representations.
		 */

		/* Build the bit length tree for the above two trees, and get the index
		 * in bl_order of the last bit length code to send.
		 */
		max_blindex = build_bl_tree( s );

		/* Determine the best encoding. Compute the block lengths in bytes. */
		opt_lenb = ( s->opt_len + 3 + 7 ) >> 3;
		static_lenb = ( s->static_len + 3 + 7 ) >> 3;
		Tracev( ( stderr, "\nopt %" PRIuSIZE "(%" PRIuSIZE ") stat %" PRIuSIZE "(%" PRIuSIZE ") stored %" PRIuSIZE " lit %u ",
				  opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
				  s->last_lit ) );
		if( static_lenb <= opt_lenb )
		{
			opt_lenb = static_lenb;
		}

	}
	else
	{
		Assert( buf != ( char* )0, "lost buf" );
		opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
	}

#ifdef FORCE_STORED
	if( buf != ( char* )0 ) /* force stored block */
	{
#else
	if( stored_len + 4 <= opt_lenb && buf != ( char* )0 )
	{
		/* 4: two words for the lengths */
#endif
		/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
		 * Otherwise we can't have processed more than WSIZE input bytes since
		 * the last block flush, because compression would have been
		 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
		 * transform a block into a stored block.
		 */
		_tr_stored_block( s, buf, stored_len, last );

#ifdef FORCE_STATIC
	}
	else if( static_lenb >= 0 )    /* force static trees */
	{
#else
	}
	else if( s->strategy == Z_FIXED || static_lenb == opt_lenb )
	{
#endif
		send_bits( s, ( STATIC_TREES << 1 ) + last, 3 );
		compress_block( s, ( ct_data* )static_ltree, ( ct_data* )static_dtree );
#ifdef DEBUG
		s->compressed_len += 3 + s->static_len;
#endif
	}
	else
	{
		send_bits( s, ( DYN_TREES << 1 ) + last, 3 );
		send_all_trees( s, s->l_desc.max_code + 1, s->d_desc.max_code + 1,
						max_blindex + 1 );
		compress_block( s, ( ct_data* )s->dyn_ltree, ( ct_data* )s->dyn_dtree );
#ifdef DEBUG
		s->compressed_len += 3 + s->opt_len;
#endif
	}
	Assert( s->compressed_len == s->bits_sent, "bad compressed size" );
	/* The above check is made mod 2^32, for files larger than 512 MB
	 * and uLong implemented on 32 bits.
	 */
	init_block( s );

	if( last )
	{
		bi_windup( s );
#ifdef DEBUG
		s->compressed_len += 7;  /* align on byte boundary */
#endif
	}

// RB begin
#ifdef _MSC_VER
	Tracev( ( stderr, "\ncomprlen %Iu(%Iu) ", s->compressed_len >> 3,
			  s->compressed_len - 7 * last ) );
#else
	Tracev( ( stderr, "\ncomprlen %" PRIuSIZE "(%" PRIuSIZE ") ", s->compressed_len >> 3,
			  s->compressed_len - 7 * last ) );
#endif
// RB end
}

/* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 */
int ZLIB_INTERNAL _tr_tally( s, dist, lc )
deflate_state* s;
unsigned dist;  /* distance of matched string */
unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
{
	s->d_buf[s->last_lit] = ( ush )dist;
	s->l_buf[s->last_lit++] = ( uch )lc;
	if( dist == 0 )
	{
		/* lc is the unmatched char */
		s->dyn_ltree[lc].Freq++;
	}
	else
	{
		s->matches++;
		/* Here, lc is the match length - MIN_MATCH */
		dist--;             /* dist = match distance - 1 */
		Assert( ( ush )dist < ( ush )MAX_DIST( s ) &&
				( ush )lc <= ( ush )( MAX_MATCH - MIN_MATCH ) &&
				( ush )d_code( dist ) < ( ush )D_CODES,  "_tr_tally: bad match" );

		s->dyn_ltree[_length_code[lc] + LITERALS + 1].Freq++;
		s->dyn_dtree[d_code( dist )].Freq++;
	}

#ifdef TRUNCATE_BLOCK
	/* Try to guess if it is profitable to stop the current block here */
	if( ( s->last_lit & 0x1fff ) == 0 && s->level > 2 )
	{
		/* Compute an upper bound for the compressed length */
		ulg out_length = ( ulg )s->last_lit * 8L;
		ulg in_length = ( ulg )( ( long )s->strstart - s->block_start );
		int dcode;
		for( dcode = 0; dcode < D_CODES; dcode++ )
		{
			out_length += ( ulg )s->dyn_dtree[dcode].Freq *
						  ( 5L + extra_dbits[dcode] );
		}
		out_length >>= 3;
		Tracev( ( stderr, "\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
				  s->last_lit, in_length, out_length,
				  100L - out_length * 100L / in_length ) );
		if( s->matches < s->last_lit / 2 && out_length < in_length / 2 )
		{
			return 1;
		}
	}
#endif
	return ( s->last_lit == s->lit_bufsize - 1 );
	/* We avoid equality with lit_bufsize because of wraparound at 64K
	 * on 16 bit machines and because stored blocks are restricted to
	 * 64K-1 bytes.
	 */
}

/* ===========================================================================
 * Send the block data compressed using the given Huffman trees
 */
local void compress_block( s, ltree, dtree )
deflate_state* s;
ct_data* ltree; /* literal tree */
ct_data* dtree; /* distance tree */
{
	unsigned dist;      /* distance of matched string */
	int lc;             /* match length or unmatched char (if dist == 0) */
	unsigned lx = 0;    /* running index in l_buf */
	unsigned code;      /* the code to send */
	int extra;          /* number of extra bits to send */

	if( s->last_lit != 0 ) do
		{
			dist = s->d_buf[lx];
			lc = s->l_buf[lx++];
			if( dist == 0 )
			{
				send_code( s, lc, ltree ); /* send a literal byte */
				Tracecv( isgraph( lc ), ( stderr, " '%c' ", lc ) );
			}
			else
			{
				/* Here, lc is the match length - MIN_MATCH */
				code = _length_code[lc];
				send_code( s, code + LITERALS + 1, ltree ); /* send the length code */
				extra = extra_lbits[code];
				if( extra != 0 )
				{
					lc -= base_length[code];
					send_bits( s, lc, extra );     /* send the extra length bits */
				}
				dist--; /* dist is now the match distance - 1 */
				code = d_code( dist );
				Assert( code < D_CODES, "bad d_code" );

				send_code( s, code, dtree );     /* send the distance code */
				extra = extra_dbits[code];
				if( extra != 0 )
				{
					dist -= base_dist[code];
					send_bits( s, dist, extra ); /* send the extra distance bits */
				}
			} /* literal or match pair ? */

			/* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
			Assert( ( uInt )( s->pending ) < s->lit_bufsize + 2 * lx,
					"pendingBuf overflow" );

		}
		while( lx < s->last_lit );

	send_code( s, END_BLOCK, ltree );
}

/* ===========================================================================
 * Check if the data type is TEXT or BINARY, using the following algorithm:
 * - TEXT if the two conditions below are satisfied:
 *    a) There are no non-portable control characters belonging to the
 *       "black list" (0..6, 14..25, 28..31).
 *    b) There is at least one printable character belonging to the
 *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
 * - BINARY otherwise.
 * - The following partially-portable control characters form a
 *   "gray list" that is ignored in this detection algorithm:
 *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
 * IN assertion: the fields Freq of dyn_ltree are set.
 */
local int detect_data_type( s )
deflate_state* s;
{
	/* black_mask is the bit mask of black-listed bytes
	 * set bits 0..6, 14..25, and 28..31
	 * 0xf3ffc07f = binary 11110011111111111100000001111111
	 */
	unsigned long black_mask = 0xf3ffc07fUL;
	int n;

	/* Check for non-textual ("black-listed") bytes. */
	for( n = 0; n <= 31; n++, black_mask >>= 1 )
		if( ( black_mask & 1 ) && ( s->dyn_ltree[n].Freq != 0 ) )
		{
			return Z_BINARY;
		}

	/* Check for textual ("white-listed") bytes. */
	if( s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
			|| s->dyn_ltree[13].Freq != 0 )
	{
		return Z_TEXT;
	}
	for( n = 32; n < LITERALS; n++ )
		if( s->dyn_ltree[n].Freq != 0 )
		{
			return Z_TEXT;
		}

	/* There are no "black-listed" or "white-listed" bytes:
	 * this stream either is empty or has tolerated ("gray-listed") bytes only.
	 */
	return Z_BINARY;
}

/* ===========================================================================
 * Reverse the first len bits of a code, using straightforward code (a faster
 * method would use a table)
 * IN assertion: 1 <= len <= 15
 */
local unsigned bi_reverse( code, len )
unsigned code; /* the value to invert */
int len;       /* its bit length */
{
	register unsigned res = 0;
	do
	{
		res |= code & 1;
		code >>= 1, res <<= 1;
	}
	while( --len > 0 );
	return res >> 1;
}

/* ===========================================================================
 * Flush the bit buffer, keeping at most 7 bits in it.
 */
local void bi_flush( s )
deflate_state* s;
{
	if( s->bi_valid == 16 )
	{
		put_short( s, s->bi_buf );
		s->bi_buf = 0;
		s->bi_valid = 0;
	}
	else if( s->bi_valid >= 8 )
	{
		put_byte( s, ( Byte )s->bi_buf );
		s->bi_buf >>= 8;
		s->bi_valid -= 8;
	}
}

/* ===========================================================================
 * Flush the bit buffer and align the output on a byte boundary
 */
local void bi_windup( s )
deflate_state* s;
{
	if( s->bi_valid > 8 )
	{
		put_short( s, s->bi_buf );
	}
	else if( s->bi_valid > 0 )
	{
		put_byte( s, ( Byte )s->bi_buf );
	}
	s->bi_buf = 0;
	s->bi_valid = 0;
#ifdef DEBUG
	s->bits_sent = ( s->bits_sent + 7 ) & ~7;
#endif
}

/* ===========================================================================
 * Copy a stored block, storing first the length and its
 * one's complement if requested.
 */
local void copy_block( s, buf, len, header )
deflate_state* s;
charf*    buf;    /* the input data */
unsigned len;     /* its length */
int      header;  /* true if block header must be written */
{
	bi_windup( s );      /* align on byte boundary */

	if( header )
	{
		put_short( s, ( ush )len );
		put_short( s, ( ush )~len );
#ifdef DEBUG
		s->bits_sent += 2 * 16;
#endif
	}
#ifdef DEBUG
	s->bits_sent += ( ulg )len << 3;
#endif
	while( len-- )
	{
		put_byte( s, *buf++ );
	}
}
